1. Field of the Invention
This invention relates to a synchronous inductance motor which starts using inductance torque and performs a synchronous operation using reluctance torque and its manufacturing method.
2. Description of the Related Art
FIG. 16 illustrates a sectional view of a motor according to the related art disclosed in Japanese Unexamined Patent Publication HEI 10-127023. In FIG. 16, a rotor 11, a slit 13, and a stator 20 are illustrated.
In FIG. 16, since a multiplicity of slits 13 in a linear shape is provided in the rotor 11, a d-axis which is an easy-to-pass direction of magnetic flux and a q-axis which is a difficult-to-pass direction of magnetic flux are shifted by 90 degrees each other, and the motor includes a two-pole magnetic polar projection. The slit 13 does not include a conductivity member (secondary conductor), and the slit 13 includes an air layer.
FIG. 17 illustrates a sectional view of a rotor of a synchronous motor packaged in a compressor according to the related art disclosed in Japanese Unexamined Patent Publication 2001-73948. In FIG. 17, a rotor 105, slots 301 and 304 filled with aluminum, and permanent magnets 300a and 300b are illustrated. In FIG. 17, a two-pole rotor includes the permanent magnets 300a and 300b arranged so that S pole, S pole, N pole, and N pole are arranged in a circumference direction of the rotor 105.
The motor according to the related art is structured as stated, and there are following problems. Since an inside of the slit 13 in the motor illustrated in FIG. 16 is not filled with the conductivity member, the rotor 11 does not have a secondary conductor in a squirrel-cage shape. Therefore, it is necessary that the stator generates a magnetic field appropriate for a position of the rotor 11, and it becomes necessary to use a mechanism for detecting a rotor position and a drive circuit. When the mechanism for detecting the rotor position is provided, a cost of the motor goes up, and a size of the motor becomes larger. Further, since the drive circuit is used, a system for driving the motor becomes large-scale, and an expensive control device becomes necessary. Hence, a cost goes up.
Further, if the position of the rotor is not detected accurately, it is impossible to stably perform the synchronous operation. Therefore, there is a problem that the cost further goes up. As explained with reference to FIG. 17, in the synchronous motor packaged in the compressor according to the related art, the slots 301 and 304 are filled with aluminum and the rotor 105 includes the secondary conductor in the squirrel-cage shape. Hence, the motor can start easily. However, since the synchronous operation is performed using the permanent magnets 300a and 300b which are expensive, there is a problem that the cost of the motor and the cost of the compressor tend to go up. Further, since the rotor 105 includes the permanent magnets 300a and 300b, when the synchronous motor is dismantled, the permanent magnets attract a dismantling device, and a dismantling operation becomes difficult.